Conventionally, on a magnetic disc apparatus, in order to move a magnetic head to an intended position on a disc with a high degree of accuracy, there are mounted a first actuator for largely moving the magnetic head to a vicinity of the intended position and a second actuator for slightly moving the magnetic head to the intended position from the position to which the magnetic head has been moved by the first actuator.
For example, FIG. 19 is a plan view showing a configuration of a conventional magnetic disc apparatus. As shown in FIG. 19, a magnetic head (not shown) is provided on a gimbal 210 connected to an end of a suspension 200, and a voice coil motor 250 as a first actuator is provided on a suspension holding member 230. Between the suspension 200 and the suspension holding member 230, there is provided a piezoelectric actuator 100 as a second actuator.
The piezoelectric actuator 100 is equipped with a cuboid-shaped piezoelectric body made of piezoelectric ceramic such as lead zirconate titanate (PZT) and external electrodes each provided on each of two mutually opposed surfaces of the piezoelectric body, and the piezoelectric body expands and contracts upon application of a voltage to the external electrodes.
In a conventional magnetic disc apparatus, a coating layer 101 made of resin is provided to cover the surfaces of the piezoelectric actuator 100, and the coating layer 101 prevents fine piezoelectric ceramic particles from falling off the piezoelectric body of the piezoelectric actuator 100. Thus, the coating layer prevents the phenomenon that, when the piezoelectric actuator 100 is driven, the fine piezoelectric ceramic particles fall off the piezoelectric body due to expansion and contraction of the piezoelectric body of piezoelectric actuator 100 and other causes, and the fallen-off particles stick to the magnetic head and a magnetic recording disc 310, whereby the reliability of writing of information in the magnetic recording disc 310 and reading-out of information from the magnetic recording disc 310 decreases (for example, see Patent Document 1).
Patent Document 1: Japanese Laid-Open Patent Publication No. 2002-163870